1. Field of the Invention
This invention relates generally to an electronic circuit device and a method of manufacturing same in which plural semiconductor elements are mutually connected using multi-layer wiring. More particularly, the invention relates to an electronic circuit device and method of manufacturing same in which multi-layer wiring is formed after arranging the semiconductor elements on a substrate.
2. Description of the Prior Art
Typical methods of forming wiring patterns are well known including: (1) applying a copper foil on a glass-epoxy substrate and etching the copper foil to form, for example, a printed circuit, (2) forming a conductive layer and an insulating layer on the substrate using vacuum evaporation or sputtering, and thereafter forming a circuit pattern using an etching process, (3) screen printing using a thick film paste, and the like.
When these conventional technologies are utilized to interconnect plural semiconductor elements on a substrate, the semiconductor elements are disposed on the substrate on which the wiring patterns have already been formed. Thereafter, a wire-bonding method is employed to connect the semiconductor elements to the wiring pattern. It has also been known to bury plural semiconductor elements into a resin substrate so that electrodes for the semiconductor elements are exposed on the same plane as the surface of the resin substrate. Thereafter, semiconductor elements are directly connected by wiring patterns. This method has an advantage of forming a thinner construction as a whole, because wire bonding is not necessary.
However, if above methods (1) through (3) are used to form wiring patterns, there are the following problems because the wiring patterns are formed on the substrate on which the semiconductor elements are already arranged. Above methods (1) and (2) need a metal etching process. As a result, the etchant can damage the semiconductor elements. Furthermore, since the resulting structure must be cleaned to eliminate residue, the manufacturing process becomes complex. Method (3) needs a high temperature curing process after thick paste printing. As a result, the high temperature may damage the semiconductor elements. These problems become more acute as the number of wiring layers increases.
Thus, in these conventional technologies, the semiconductor elements may be damaged from the etchant and the high temperature as the semiconductor elements are interconnected using multilayer wiring after the semiconductor elements are arranged on the substrate.